RESUMEN
The occurrence of pigmented bacteria in potable water, from raw source water through treatment to distribution water, including dead-end locations, was compared at sample sites in a large municipal water system. Media used to enumerate heterotrophic bacteria and differentiate pigmented colonies were standard method plate count (SPC), m-SPC, and R2A agars, incubated up to 7 days at 35 degrees C. The predominant pigmented bacteria at most sample locations were yellow and orange, with a small incidence of pink organisms at the flowing distribution site. Seasonal variations were seen, with the yellow and orange organisms shifting in dominance. SPC agar was the least productive medium for both heterotroph counts and pigmented bacteria differentiation. At the flowing distribution site, percentages of pigmented bacteria on SPC medium ranged from 2.3 to 9.67 times less than on m-SPC and from 2.3 to 9.86 times less than on R2A. At the same site, seasonal trends in the percentage of pigmented bacteria were the same for m-SPC and R2A media, and the highest and lowest percentages occurred in the fall and winter, respectively. At site 6, there appeared to be an inverse relationship between the yellow and orange pigmented groups, but upon analysis, this did not hold and all correlations between yellow and orange pigmented bacteria were positive. The study results indicate that pigmented bacteria could readily be detected by using plate counting media developed for heterotroph enumeration in potable waters with incubation periods of 7 days. Pigmented bacteria can be used as an additional marker for monitoring changes in water quality. High numbers of heterotrophs, including pigmented forms, were found at dead-end locations, usually in the absence of a free chlorine residual and when the water temperature was greater than 16 degrees C. The association of some pigmented bacteria with nosocomial and other infections raises concern that the organisms may have originated from the potable water supply. High levels of pigmented bacteria could pose an increased health risk to immunologically compromised individuals. Therefore, the bacterial quality of the distribution water should be controlled to prevent the development of high concentrations of heterotrophic plate count bacteria, including the pigmented forms.
Asunto(s)
Bacterias/crecimiento & desarrollo , Microbiología del Agua , Abastecimiento de Agua , Análisis de Varianza , Recuento de Colonia Microbiana , Medios de Cultivo , Agua Dulce , Pigmentos Biológicos/biosíntesis , Estaciones del AñoRESUMEN
The structure of fermentation product A 19009 was reinvestigated by 13C and 1H NMR spectroscopy and established by independent synthesis to be N2-L-alanyl-N3-fumaramoyl-L-2,3-diaminopropanoic acid (2), i.e. a structure isomeric with the originally proposed structure 1. In contrast to 1 which also was synthesized, 2 has a very low activity against Trichomonas vaginalis.
Asunto(s)
Antibacterianos/aislamiento & purificación , Péptidos , Dipéptidos/aislamiento & purificación , Concentración de Iones de Hidrógeno , Indicadores y Reactivos , Espectroscopía de Resonancia Magnética , Streptomyces/crecimiento & desarrolloRESUMEN
A preliminary study was carried out on evaluating a flow-through gauze sampler for its efficiency in recovering virus from both fresh and seawater. An attenuated type 1 poliovirus was used as the working model. When tap water was sampled, the amounts of virus adsorbed by the gauze pads were very small, about 2% of the total number of virus particles flowing through the device. The virus adsorption and recovery increased to 15 to 19% when seawater was sampled. Addition of NaCl to tap water produced a much better effect on virus adsorption and recovery by this device, i.e., 47% of the total virus particles in each sample. The best viral elution from the pads was obtained by using buffer solution of pH 8.0 to 9.0 containing a small amount of animal serum. Repeated elutions from the pads were necessary to recover the most virus although the first eluate contained approximately 50% of the adsorbed virus. Further development of this device appears warranted, because of (i) the simplicity of the procedure, (ii) its capability of sampling large volume of water, (iii) the low cost of collecting samples, and (iv) the feasibility of obtaining a rough quantitative assessment of viral pollutants in water examined.
Asunto(s)
Poliovirus/aislamiento & purificación , Microbiología del Agua/instrumentación , Contaminación del Agua , Adsorción , Animales , Bovinos , Gossypium , Concentración de Iones de Hidrógeno , Sueros Inmunes , Métodos , Modelos Biológicos , Agua de Mar , Cloruro de SodioRESUMEN
A study was carried out to further evaluate the practicability of viral depuration by assaying individual shellfish. The Northern quahaug and a strain of the type 1 attenuated poliovirus were used as the working model. Two types of depuration systems were employed: the small experimental tanks and a pilot-size tank with a capacity of approximately 24 bushels (836 liters) of shellfish. Volumes of the individual shellfish samples were found uniform throughout the experiments when a prior selection for the weight of the shellfish was made. There was also no significant difference in volumes of the individual samples during the course of depuration (24 to 96 hr). Under controlled hydrographic conditions, however, the uptake of virus in individual shellfish varied considerably. In general, the individual variability reached 10- to 100-fold. This wide variation would explain the variability of viral contents obtained in pooled samples during depuration as reported previously. During a later phase of depuration, although a great majority of shellfish were free of the virus, a few still harbored minimal amounts of contaminants. The presence of virus in some of the shellfish after various periods of depuration would, theoretically, be obscured by the pooling of the sampled shellfish. Further examination of the negative samples by assaying larger quantities than those routinely used revealed that a few still contained virus. To simulate naturally polluted shellfish as closely as technically possible, shellfish were polluted with minimal amounts of virus. The shellfish were cleansed more rapidly by the depuration process than were those polluted with more virus. Since the naturally polluted shellfish were shown to contain less virus than those studied in the laboratory, it is anticipated that the former type of shellfish may be cleansed more readily by this process within a reasonable period of time. Justification for a field trial of depuration in this country is presented.